Evening Primrose Oil
What is it? Overview Usage Side Effects and Warnings

Evening Primrose Oil Side Effects and Warnings

Written by ritasharma, maria_rn.

Evening primrose oil is generally well tolerated when taken in recommended dosages. Incidence of side effects is low.

Side Effects

The reported side effects that occur with evening primrose oil use include:

  • nausea,
  • headache
  • indigestion
  • stomach pain
  • soft stools
  • Stomach discomfort and loose stools may be indications that the dosage is too high. If any of the side effects persist or worsen, contact your health care provider immediately.

If you develop signs of an allergic reaction such as hives, difficulty breathing, swelling of your face, lips, tongue, or throat, you should stop taking evening primrose and seek emergency care.


Evening primrose oil should not be taken by patients who have allergies to its components. If any of the conditions below applies to you, do not take evening primrose without the advice of a doctor:

  • epilepsy or a seizure disorder
  • schizophrenia
  • bleeding problems or blood-clotting disorder
  • plans to have any type of surgery

Talk to your health care provider if you are pregnant or plan to get pregnant during the treatment. It is not known whether evening primrose could pass into breast milk or if it is harmful for a nursing baby. If you are breastfeeding, ask your doctor before using evening primrose.

Drug interactions

Evening primrose oil may alter the effects of some medications. If you are taking any of the following medications, you should not use evening primrose oil without first consulting with your doctor:

  • medicines used for psychiatric disorders, such as chlorpromazine (Thorazine), perphenazine (Trilafon), fluphenazine (Permitil, Prolixin), prochlorperazine (Compazine, Compro), promethazine (Pentazine, Phenergan, Phenadoz, Promethegan), thioridazine (Mellaril), or trifluoperazine (Stelazine). Using these drugs with evening primrose oil may increase the risk of seizures.
  • Blood thinners such as warfarin (Coumadin)
  • Anti platelet drugs* such clopidogrel (Plavix);
  • Herbs with known blood thinning properties;
  • Aspirin or other non-steroidal anti-inflammatory drugs (NSAID's)

You should inform your doctor about all your prescription and over-the-counter medications.



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